Intracellular recordings from cat's trigeminal and dorsal root ganglion cells and from dorsal root afferent fibers were made under barbiturate anesthesia. Functional characterization of the response to natural stimuli and to electrical shocks, was followed by horseradish peroxidase (HRP) deposition in the cell body or fiber. The labeled cell and the central terminal projections of the axonal arbors, in the histochemically reacted tissue, were recovered at the light microscopical level. Analysis of the labeled structures, reconstructed in the parasagittal plane, enabled the categorization of different termination sites for various functionally characterized afferent fibers.